There are several ways that you could investigate the composition of inks. This is an outline of the required steps to undertake one of these methods.
To identify the mixture of dyes in a sample of unknown composition.
Record your results in a suitable table. For example:
|Ink||Spot colour||Distance travelled by spot (mm)|
Explain why the distances travelled by each spot were measured in mm, rather than in cm.
Measurements in millimetres are more precise than those in centimetres. They will give more precise Rf values.
It is important in this practical activity to use appropriate apparatus and methods. This includes the safe use and careful handling of substances. Eye protection must be worn.
Evaluate the hazards and the precautions needed to reduce the risk of harm. For example:
|Hazard||Possible harm||Possible precaution|
|Harmful solvent||Skin irritation||Avoid skin contact, eg wear gloves|
|Harmful solvent||Breathing difficulties||Ensure adequate ventilation or use a fume cupboard|